In the centerless grinding art, when it is not convenient to have a part axially advance across the face of a grinding wheel, as during a "throughfeed" grinding operation, it may be necessary to perform what is called an "infeed" grind operation, wherein the workpiece is axially stationary while being ground. A typical example of a part which lends itself to an infeed grinding operation is a ring which has a generally toroidal profile, that is, non-cylindrical. When grinding thin parts, it is often convenient to stack them and simultaneously grind a plurality of workpieces. When a cylindrical regulating wheel is employed, the wheel is radially fed toward the grinding wheel, causing all parts to be shaped at the same time, to the same diameter. A novel prior art centerless grinding machine has been employed for infeed grinding of profiled surface parts by tapering the regulating wheel so that as the regulating wheel is advanced toward the grinding wheel, the shaped parts will have progressively stepped diameters, from a rough, stack-entering workpiece; to a smaller diameter, finished stack-exiting workpiece. After each grinding operation, the workpieces and regulating wheel are retracted from the grinding wheel and the workpiece stack is advanced to the next subsequent grinding station. However, one difficulty is inherent in this method of progressively producing the stacked workpieces, in that since the regulating wheel is linearly fed towards the grinding wheel, the same amount of grinding stock is removed from each workpiece in the same time interval.
In grinding art, it is generally preferable to rough grind a relatively large amount of stock from a workpiece per unit time, shaping it to a predetermined diameter, then later finish grinding the workpiece by removing a relatively small amount of stock per unit time from the predetermined intermediate diameter to the finished size, since wheel pressures and resulting deflections of the workpiece will be lessened during the finish grinding operation and the workpiece will tend to have a truer size and shape and better surface finish.
Applicant has obviated the difficulties inherent in the prior art design by employing a curvilinear regulating wheel profile which conforms generally to a stack of progressively reduced work sizes ranging from a largest size at an inlet end between the wheels to a smallest size at an outlet end between the wheels, wherein feeding is accomplished by pivoting the regulating wheelhead about a pivot point near the outlet end of the wheel. In this pivoting manner, the feed movement or feed arc is proportional to the distance from the pivot point to the successive workpieces. Thus, a coarse feed movement at the inlet end and a fine feed movement at the outlet end is achieved, with respective proportions therebetween along the wheel face. The pivot point, work support and regulating wheel are compensatingly movable in a linear direction toward the grinding wheel to adjust the work stack to the grinding wheel face after the grinding wheel has been conditioned by a suitable dressing means.
It is therefore an object of the present invention to provide a relatively simple feed mechanism for a stack of workpieces, which accomplishes varying feed and rate increments at the respective workpieces from an inlet end to an outlet end between the wheels.